The purpose of this study was to determine whether a breakfast cereal with high soluble fiber content and moderate glycemic index could facilitate a glucose sparing effect on muscle and liver and enhance exercise performance. Hepatic glucose output was determined using a [6,6-2H] glucose tracer. We conclude that ingestion of a high soluble fiber, moderate glycemic breakfast cereal, 45 min before exercise, does not alter exercise performance when plasma FFA are suppressed and carbohydrate utilization is increased during the first two hours of the exercise period.